When he turned on the bathroom light in his Clementi flat one day last month, analyst Kevin Fong was horrified to see his glass shower cubicle in smithereens all over the floor.

The tempered glass panel, which was fine when the family left home hours earlier, had shattered, mostly into tiny fragments.

"I contacted the supplier the next day and we suspect that there was a problem during installation so it was missing a bracket, which made the glass wobble beyond its usual threshold," said Mr Fong, a father of two.

The shower cubicle had been installed just over two years ago, he said.

While Mr Fong and his family were lucky to not be injured, others were not as fortunate.

Last week, a Coroner's Inquiry into the death of Mr Sebastian Wong, 24, revealed that he died in January after he fell on to the glass door of a shower cubicle, and sharp fragments pierced his neck.

Not exactly, said Mr Gary Lee, business development manager of Singapore Safety Glass (SSG), which supplies treated glass to builders around the world.

SSG's local projects include the Supreme Court, River Safari and Changi Airport Terminal 3.

Mr Lee noted that in Mr Wong's case, the shower screen had been made of heat-strengthened glass instead of tempered glass.

"When tempered glass breaks, it shatters into smaller pieces which have 'softer' edges, such that even if you get cut, it's less serious than 'ordinary' glass, which has very sharp edges," he said.

SHATTERED

On the other hand, heat-strengthened glass breaks into shards similar to untreated glass, or annealed glass, said Mr Lee.

"When people refer to safety glass, it's only two types: tempered glass or laminated glass. One big misconception has been that any glass becomes 'safety glass' just because safety film has been applied on it," he said.

A safety film is a large piece of sticky tape pasted over glass to hold the shards together in case it breaks.

But it provides a false sense of security because if the glass has not been treated properly, it can still cut through the film and hurt someone badly, he added.

Interior designer Ian Teo, who has 16 years of experience in the industry, said the industry standard has been to use tempered or laminated glass within homes, especially for bathrooms and areas which may see high traffic.

"While clients might want to use normal untreated glass because it's cheaper, I would advise them to use either tempered or laminated glass simply because it is safer," Mr Teo said, adding that for the more cost conscious, he would make provisions in his designs for the glass to be put in areas where there is a low chance of breaking, such as a display cabinet.

Laminated and tempered glass can cost up to 50 per cent more than untreated glass, said Mr Teo, adding that one can check whether one has treated glass installed by checking the corner of a glass panel for the manufacturer's mark.

While there are regulations for types of glass that can be used for the exterior of a building such as windows and at balconies, the type of glass used within the home is up to the home owner.

For instance, home owners who want to fit their windows with tempered glass- which has a tendency to spontaneously shatter - have to ensure the shards do not fall to the ground should the glass panel break.

As for Mr Fong, who has since had the shower cubicle replaced, this is scant comfort.

"With all the cases of tempered glass spontaneously shattering in toilets, I hope the authorities will take note and perhaps regulate this area more," he said.

Types of glass

Singapore Safety Glass business development manager Gary Lee explains the most common choices of glass available.

ANNEALED GLASS

Also known as untreated glass or "regular glass", this comes straight from the producers. It breaks into large shards with sharp edges that can cut and also impale.

HEAT-STRENGTHENED GLASS

Glass is heated to about 650 deg C before it is gradually cooled.

This creates surface and edge compression, which makes the glass about twice as strong as untreated glass.

While the final product can withstand high heat and strong winds, it breaks into large shards, much like annealed glass.

The plus side of this is that if used in a window, the pieces would stay within the frame and not crumble into small pieces like tempered glass.

TEMPERED GLASS (ABOVE)

Heated to 650 deg C, it is blasted with cold air to cool it rapidly, which makes it about four to five times stronger than untreated glass.

Also known as safety glass, it shatters into tiny pieces when broken, ensuring there are no big pieces with sharp edges.

But it can shatter suddenly on its own from stress if not properly installed, or if there is presence of the impurity, nickel sulphide.

LAMINATED GLASS

Made from layers of toughened glass and plastic bonded together, it helps the glass shards stay in place when broken so it does not break into large, sharp pieces.

There is a characteristic "spider web" cracking pattern when the impact is not enough to completely pierce the glass, usually seen when the front windshield of a car is smashed.